A sandwich panel combines high strength, inherent rigidity and minimum weight. For this reason it is used extensively in the aircraft industry. Of primary importance to successful utilization of a sandwich panel is the method of transmitting loads into and out of it. By their very nature, sandwich panels cannot carry concentrated unit loading. Fastener inserts have been developed for use with these panels. The present invention relates to improvements in molded-in type fastener inserts.
A prior art insert and a prior method of installing such insert have been illustrated and will be hereinafter described. Such prior art fastener element is typical of the fastener elements which have heretofore been used with both sandwich panels constructed of metal and sandwich panels constructed from composite material. A problem with the prior art insert is that it is constructed from a metal and the resin used for securing it within the sandwich panel does not bond to the metal. As a result, the fastener element is only held in place by a mechanical interlock which is formed between the resin and flange portions of the fastener element. Owing to the construction of the prior art fastener elements, often times air spaces or voids are formed in the potting resin, producing a weakened connection.
The principal object of the present invention is to provide an improved fastener element and a method of installing such fastener element which will result in a stronger connection of the fastener element to the sandwich panel and an elimination or reduction in size of airspaces or voids in the potting resin.